PREIMPLANTATION GENETIC DIAGNOSIS (PGD)

PGD can be performed only on embryos in vitro (in a laboratory). That means this test is always performed in conjunction with an in vitro fertilization cycle.

CHORIONIC VILLUS SAMPLING (CVS)

Chorionic villus sampling (CVS) is a relatively new procedure used to diagnose certain birth defects in the first trimester of pregnancy. The test has been performed regularly since 1982, and many thousand have been performed around the world. CVS is a prenatal test that involves taking a tiny tissue sample from outside the sac where the fetus develops. This tissue contains the same genetic material as the fetus.